Gov. Martin O'Malley announced Friday that he is calling lawmakers back to Annapolis for a special session of the General Assembly to complete work on budget-related bills  that failed to win approval  before the clock ran out on the regular 90-day session that ended April 9.

The governor's announcement came as no surprise after Senate President Thomas V. Mike Miller said Wednesday that he had asked senators to set aside May 14-15 for what he hoped would be a brief session.

O'Malley said the special session will be held to make sure Maryland’s Triple A bond rating is protected and to protect what he called "critical investments" in public education, public safety, the state’s work force and social services.

"There is too much at stake not to move forward,” the governor said in a news release. “I’m confident that we can come together with the Senate president and House speaker to complete this most important work for the people of our State.”

The governor's office said O'Malley, the Senate President Thomas V. Mike Miller and House Speaker Michael E. Busch will hold a press conference next week to discuss the session.

During the session lawmakers are expected to take up a tax-increase bill and a budget reconciliation measure, which includes a shift of some teacher pension costs to the counties.  Unless those measures are adopted, a so-called Doomsday Budget with about $500 million in cuts the majority Democrats want to avoid, would go into effect July 1.

O'Malley's announcement indicates that House and Senate leaders have reached substantial agreement on what they intend to do -- and not do -- during the session. The governor previously said he did not intend to call a special session unless the two chambers had reached a consensus on the issues that divided them until the last night of the regular session.

It was not until about 8 p.m. that night that a House-Senate conference committee reached an agreement on an income tax increase bill, which was also holding up the reconciliation measure. But against the backdrop of a squabble between the two houses over a gambling-expansion bill, the budget-related compromises did not receive final approval before the midnight deadline.

In the weeks after the session ended, some senators -- dissatisfied with a  compromise that mostly reflected the House's desire to limit the increase to high-income Marylanders -- talked about reopening the conference to negotiate a new deal. But Busch has insisted that the two sides had an agreement that he expects will be honored, and Democratic senators this week appeared resigned to a final deal along the lines of the conference committee compromise.

That compromise calls for income tax increases to be limited to individuals earning more than $100,000 and couples making $150,000 or more. The Senate had preferred a more broad-based increase, but by signing off on the conference report its negotiators have already shown what they would settle for.

If the two chambers come in with a prearranged deal and both pass the legislation without amendments, it is entirely possible that the bills can be pushed through in a day or two. It the House and Senate get hung up on unresolved details, the session could drag on at an estimated $25,000 a day while Republicans call attention to the mounting expense.

House Minority Leader Anthony J. O'Donnell has said Democratic leaders must be "out of their minds" to call a special session to raise taxes.

The issue of gambling, which complicated the last days of the regular session, is virtually certain to remain off the table during the special session. Though Miller has continued to argue in favor of table games and an additional casino, Busch has said more time is needed to study the issue and O'Malley has proposed that it be taken up in a possible second special session in late summer.

Miller has pledged that gambling will not be allowed to hang up any budget deal.